orthogonal

Orthogonal

Two vectors are orthogonal if their dot product is zero, i.e. they are perpendicular to each other:

$$\mathbf{a}\cdot \mathbf{b}=0⟹\mathbf{a}\perp \mathbf{b},\mathbf{a},\mathbf{b}\in {\mathbb{R}}^n$$

So the angle between them is $90^{\circ }$.